The circular tube with the cross section shown is subjected to the axial force P and bending moment M, both directed as shown. Using the readings from the strain gages at a and b, the corresponding stresses at these locations are calculated to be a = 2800 psi and ob = -15100 psi. Compute P and M. P M b a FIG. P8.19 M P 2 in. 101 1.75 in.